SENTINEL SURVEILLANCE FOR HIV-1 INFECTION - HOW REPRESENTATIVE ARE BLOOD-DONORS, OUTPATIENTS WITH FEVER, ANEMIA, OR SEXUALLY-TRANSMITTED DISEASES, AND ANTENATAL CLINIC ATTENDERS IN MWANZA REGION, TANZANIA

Objective: To assess the validity of extrapolation from sentinel data by comparing the HIV-1 prevalence of various sentinel groups with that of the general population in Mwanza Region, Tanzania. Methods: In a p opulation survey, 4161 individuals were selected in a stratified rando m cluster sample. Sentinel groups (all in the age group 15-54 years) i ncluded blood donors (n = 1090); patients examined at district hospita ls for the presence of malaria parasites (n = 1488), anaemia (n = 1339 ), or syphilis (n = 33); and antenatal clinic attenders (n = 1193). Th e HIV-1 serostatus of individuals selected from the population survey was tested using enzyme-linked immunosorbent assay (ELISA) and Western blot; 51% of the blood donors were tested using HIVCHEK, and all othe rs using ELISA. HIV-1 prevalence was standardized for age, sex, and ur ban/non-urban location. Results: HIV-1 prevalence (standardized by age , sex, and residence) in Mwanza Region was 4.0% (3.0% in non-urban are as and 11.3% in town). The standardized HIV-1 prevalences in the senti nel groups were: blood donors, 4.5%; patients with fever, 11.6%; patie nts with anaemia, 8.9%; urban sexually transmitted disease patients, 2 7.1%; urban antenatal clinic attenders, 11.8%. The crude prevalence in blood donors was 6.0%. Conclusion: Blood donors who are related to bl ood recipients appear to be a representative sentinel group in this re gion, provided that data are standardized for age, sex, and urban/non- urban location. Patients with fever and antenatal clinic attenders may reflect trends, but data from patients with fever markedly overestima te, and data from antenatal clinic attenders underestimate, population HIV-1 prevalence. Because self-selection of blood donors may become m ore pronounced, this comparison should be repeated later or elsewhere, should the opportunity arise.